The present invention relates to a gripping part such as a steering wheel and a grip, having a soft feeling equivalent to foaming RIM urethanes and having excellent sweat resistance, without the need of coating, which solves problems involved in RIM (reaction injection molding) polyurethanes including low productivity, low recycling property, and the like.
Conventionally, as a steering wheel and a grip (a shift lever grip, a door grip, a door upper part grip to be used at the time of getting on or off, a side brake lever, or the like) for the automobile interior, and a grip (handle) for a bag, those produced by covering an inserted metal core with a rigid resin material such as a polypropylene (PP) and a polyvinyl chloride (PVC) have been used. However, since the solid molded products of PPs or PVCs have a hard gripping feeling, they are scarcely used practically in the present situation. In contrast, since the foaming RIM urethane has excellent feeling, the material is used in most of steering wheels and grips at the present. However, the foaming RIM urethane involves problems of a long molding cycle and a poor yield, and furthermore, a problem of a poor recycling property since it is not thermoplastic. Then, steering wheels and grips using a soft material in place of the foaming RIM urethane have been variously proposed. JP-A-5-294247 (The term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined Japanese patent applicationxe2x80x9d) proposes a steering wheel produced by molding an ester based or polyurethane elastomer having a surface hardness of from 60 to 99 in accordance with JIS K7215 type A or of 25 to 80 in accordance with JIS K7215. However, compared with the foaming RIM urethane, these steering wheels have insufficient soft feeling and sweat resistance, and furthermore, they are not sufficient also in terms of achieving a light weight.
Moreover, JP-A-8-183041, JP-A-6-170882 disclose a steering wheel comprising an olefin based or styrene based thermoplastic elastomer cover. Compared with the ester based or urethane based thermoplastic elastomers, the olefin based or styrene based elastomer can provide a low hardness so as to obtain a soft feeling, however, compared with a foaming urethane steering wheel, the feeling at the time of gripping differs (the initial stress is large), and thus it is insufficient in terms of the feeling. Moreover, since the olefin based, styrene based thermoplastic elastomer has a poor abrasion resistance, a problem of wearing out is involved in the case of a steeling wheel or a grip, which always comes in contact with a hand.
An object of the present invention is to provide a gripping part such as a steering wheel and a grip, having soft feeling and excellent surface outer appearance, further, being superior to the conventional products in ye the soft feeling, sweat resistance, abrasion resistance, light resistance and the oxidation deterioration resistance, and having a good elastic recovery property as a molded product such as a steering wheel and a grip.
The invention provides a gripping part, such as a steering wheel and a grip, comprising a foamed product of a thermoplastic elastomer with a 1.1 to 8.0 times expansion ratio, having a feature that the thermoplastic elastomer is a polyurethane elastomer produced by copolymerizing the following (a), (b) and, as needed, C):
(a) a polymer polyol which is an aliphatic polycarbonate comprising repeating units of the following formulae (1) and (2), with the ratio ((1)/(2)) of (1) to (2) being 10/90 to 90/10 (molar ratio) (wherein n is an integer of 4 and/or 5), 
(b) a polyisocyanate; and
(c) a chain extending agent reactive with the polyisocyanate.